A user equipment (UE, also called as user terminal or terminal) of machine type communication (MTC) is also called as machine to machine (M2M) user communication equipment, which is a main application form in current Internet of things. In recent years, since long-term evolution (LTE)/long-term evolution advance (LTE-advance or LTE-A) has high spectral efficiency, more and more mobile operators select LTE/LTE-A as an evolution direction of a broadband wireless communication system. Various MTC data services based on LTE/LTE-A will be more attractive.
In an existing LTE/LTE-A system, transmission is performed by dynamic scheduling based on each subframe, i.e. each subframe can transmit different control channels.
A physical downlink control channel (PDCCH) and an enhanced physical downlink control channel (EPDCCH) are defined in LTE/LTE-A. Information carried in a physical control format indicator channel (PCFICH) is used for indicating the number of orthogonal frequency division multiplexing (OFDM) symbols of the PDCCH transmitted in one subframe. A physical hybrid-automatic repeat-request (ARQ) indicator channel (PHICH) is used for bearing acknowledge/negative acknowledge (ACK/NACK) feedback information of uplink transmission data. The downlink control channel adopts blind detection, and a terminal tries to demodulate the downlink control channel by virtue of different aggregation levels and candidates in a certain search space.
An existing UE-specific search space is shown in Table 1 and Table 2. The search space is composed of candidates corresponding to different aggregation levels. The terminal needs to demodulate each of the candidates until demodulation is accurate while demodulating the control channel, otherwise it should be believed that a control channel belonging to the UE is not received.
TABLE 1Search space Sk(L)Number of PDCCHTypeAggregation level LSize [in CCEs]candidates M(L)UE-specific16621264828162
The search space of the EPDCCH (One Distributed EPDCCH-PRB-set—Case 3) is shown in Table 2:
TABLE 2Number of EPDCCH candidates Mp(L) for Case 3NRBXpL = 1L = 2L = 4L = 8L = 16284210445421844422
The PDCCH/EPDCCH is used for bearing downlink control information (DCI) including uplink and downlink scheduling information and uplink power control information.
Generally, a MTC terminal can obtain the DCI by demodulating the PDCCH/EPDCCH in each subframe, thereby realizing demodulation of a physical downlink share channel (PDSCH) and obtaining scheduling indication information of a physical uplink share channel (PUSCH).
Among MTC application terminals, one type of terminals cannot receive signals or channels transmitted in full bandwidth and coverage performance thereof is obviously decreased due to limited radio frequency reception bandwidths and limited locations or self-characteristics. For example, most of intelligent meter-reading MTC terminals are fixedly installed in a basement or other low-coverage-performance environments, mainly transmit packet data, have a low requirement on data rate and can tolerate a great data transmission delay. Since such type of terminals has low requirement on the data rate, with respect to a data channel, accurate transmission of the packet data may be ensured in manners such as a low modulation coding rate, repeated transmission in time-domain and the like.
With respect to a problem of receaving and detecting a control channel by a coverage-enhanced MTC terminal in case of transmission at different repeat times in the existing art, no effective solution exists at present.